The Neuroscience Center Behavior Core will establish a centralized resource for the analysis of animal behavior. The objectives of this core resource will be to provide uniform behavioral analysis of rodents employing a variety of behavioral platforms appropriate for the research needs of Salk Institute Neuroscience Center faculty and to provide expertise for the interpretation of results. Behavioral studies are an important component of modern neuroscience research. For example, careful analysis of changes in rat behavior in the radial water maze showed that the ability to learn new tasks decreases with age. These changes were eventually found to be reflected at the cellular level, in particular, in the dentate gyrus of the hippocampus where aging is associated with a reduction in the number of axons in the medial perforant path, as well as the density of synaptic contacts impinging on granule cells. Subsequently this reduction in the input to the hippocampus was found accompanied by a decrease in synaptic plasticity, longterm potentiation has a higher threshold and lasts for a shorter time in aged animals, and there is an agedependent decrease in NMDA receptor-mediated responses - all discoveries stemming from the initial analysis of animal behavior.